From CVID to PIRD: Genetic testing Leading to Signal Transducer and Activator of Transcription (STAT) 3 Gain-of-Function Diagnosis and Directed Therapy.

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary antibody deficiency. For unclear reasons, inflammatory complications, like gastrointestinal (GI) disease, occur in ~50% of CVID cases, worsening morbidity and mortality. NFKB1 variants are among the most frequent genetic variants in CVID. While effect of NFKB1 variants is not well understood, we previously found frameshift heterozygous NFKB1 variants to increase cytokines, monocytes, and inflammatory complications in CVID. In this report, we used induced pluripotent stem cell-derived (iPSC-derived) monocytes (iMONOs) with CRISPR/Cas9-mediated gene editing to study a heterozygous NFKB1 frameshift found in a patient with CVID with severe GI disease. The heterozygous NFKB1 variant similarly reduced NFKB1 protein in CVID patient- and healthy donor-derived iMONOs, but elevated LPS-induced IL-1β release and expression of inflammatory genes, including IL1B, IL6, TNF, and neutrophil chemoattractants, only in CVID patient iMONOs. CVID patient iMONOs also had elevations of IL-12, CCL4, and CCL12 unaffected by presence or absence of the NFKB1 variant. TNF antagonism improved the patient's GI disease, diminishing neutrophilic gastritis, circulating neutrophils, and the neutrophil chemoattractant CXCL1 in the blood. While the biology remains complex, our approach found heterozygous NFKB1 variant-induced inflammatory changes intensified in CVID iMONOs, corresponding with clinical response to TNF antagonism.

Serum free light chains (sFLCs) have recently been introduced as a diagnostic biomarker in common variable immunodeficiency (CVID) patients. Most patients with CVID have undetectable or lower levels of sFLCs compared to people with other types of immune system deficiencies with hypogammaglobulinemia, except for patients with agammaglobulinemia (AGG). Decreased production of kappa (κ) and lambda (λ) light chains over immunoglobulins (Ig) suggests a malfunction in early B cell development or plasma cell dysfunction may cause CVID. In this cross-sectional study, immunoturbidimetry was used to measure sFLCs in 70 immunodeficiency patients, including 39 patients with CVID, 31 patients with other immunodeficiencies with hypogammaglobulinemia such as combined immunodeficiency (CID), AGG, and other primary immunodeficiencies (PIDs), and 20 healthy controls. The levels of both κ and λ chains were significantly higher in patients with CID than patients with CVID and AGG patients (p < 0.05). The median (Q1–Q3) κ level in patients with other primary immunodeficiency disorders (PIDs) was significantly higher than that observed in patients with AGG and CVID (p < 0.01). Similarly, the median (Q1–Q3) λ level was higher in patients with other PIDs compared with those with AGG and CVID (p < 0.05).ROC analysis of κ and λ disclosed an area under the curve (AUC) for κ was 0.98 (95% CI: 0.96–0.99, p < 0.0001) and for λ was 0.95 (95% CI: 0.89–0.99, p < 0.0001) in patients with CVID. The sFLCs test can help distinguish between CVID and other immunodeficiency patients with hypogammaglobulinemia and the diagnosis of hypogammaglobulinemia.

ABSTRACTThe link between allergic conditions and common variable immunodeficiency (CVID) is still unclear. Only a few studies suggest allergic diseases are more prevalent in CVID patients than in the general population, and the role of IgE remains poorly defined. This study aims to evaluate the prevalence of allergic conditions in CVID and the role of serum IgE and IgA levels. This prospective, cross‐sectional, case–control study enrolled Italian adult CVID patients to investigate allergic conditions' frequency and relationships between IgE, IgA, and clinical phenotypes. Analyses of diagnostic/prognostic accuracy were performed with ROC curves. We documented an allergic disease in 26.6% of 60 CVID patients, most commonly allergic rhinitis (56.2%) and bronchial asthma (12.5%). CVID patients with allergy had higher IgE levels (+8.9 kU/L, p = 0.006) than non‐allergic ones, but lower than allergic individuals without CVID. IgE deficiency was observed in 65% of CVID patients, with a strong correlation between IgE and IgA levels (r = 0.7, p < 0.001). Low IgE (< 2.5 kU/L) and IgA levels (< 7 mg/dL) were significantly associated with lymphoproliferative (p < 0.001) and granulomatous phenotypes (p = 0.005), achieving an AUC of 94% and 81% for predicting lymphoproliferation and granulomatosis, respectively. The prevalence of allergic conditions in CVID patients is lower compared with previous studies. Low IgE levels served as a good biomarker for CVID and CVID‐phenotypes. Combined serum IgE and IgA assessment improved prognostic stratification.

Background. Common Variable Immunodeficiency (CVID) is a primary immunodeficiency disorder characterized by B-cell dysfunction and immunoglobulin production deficiency. Dysregulation of interleukin-17 (IL-17) and its receptor IL-17RA have been reported in various immune disorders. This study aimed to investigate the expression of IL-17RA in innate immune cells of CVID patients and its correlation with clinical manifestations. Methods. A cross-sectional study included 22 CVID patients and 14 age- and sex-matched healthy controls. IL-17RA expression was assessed in various immune cell subsets using flow cytometry. Demographic and clinical data were collected, and statistical analysis was performed. Results. CVID patients had elevated IL-17RA expression in neutrophils, non-classical monocytes, and dendritic cells compared to healthy controls. Patients with a history of intestinal microbial colonization, particularly with Campylobacter jejuni and Giardia intestinalis, showed significantly higher IL-17RA expression in innate cells. Elevated IL-17RA expression in monocytes and dendritic cells also correlated with higher fecal calprotectin levels in CVID patients, regardless of microbial colonization. Conclusions. The study suggests that despite previous reports of reduced circulating Th17 cells and IL-17 levels in CVID patients, IL-17RA expression in innate cells may be elevated, potentially indicating altered IL-17 signaling. This heightened IL-17RA expression could contribute to a persistent pro-inflammatory state, possibly due to microbial translocation or other inflammatory factors. The association of IL-17RA expression with gastrointestinal microbial colonization and its correlation with fecal calprotectin underscores the complexity of IL-17RA's role in CVID pathophysiology. Further research in larger cohorts could elucidate the implications of IL-17RA expression in both infectious and non-infectious inflammatory aspects of CVID.

Background: Common variable immunodeficiency (CVID) is the most frequent symptomatic primary antibody deficiency, associated with recurrent infections, immune dysregulation, and non-infectious complications. Amyloidosis is a rare but severe complication with pulmonary involvement being exceptional. Objective: The aim of this study was to review reported cases of amyloidosis complicating CVID and present a unique case of pulmonary involvement. Methods: A literature research identified observational studies and case reports linking amyloidosis with CVID. Additionally, we describe a patient with CVID complicated by pulmonary and gastrointestinal amyloidosis. Results: Fifteen cases were identified, mostly amyloid A (AA) with multiple organ involvement. Only one case of pulmonary amyloidosis was reported. To date, no cases of pulmonary light-chain amyloidosis (AL) have been described in CVID patients without an underlying plasma cell dyscrasia. Our patient initially presented with AA amyloidosis but evolved to systemic AL type with rapid progression and fatal outcome despite therapy. Conclusions: Amyloidosis should be considered in CVID patients with atypical symptoms. Accurate amyloid typing is essential as treatment differs between AA and AL types. Early recognition may improve outcomes.

Immunologic biomarkers of noninfectious complications and overall survival in common variable immunodeficiency.

Background: Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency in adults, characterized by reduced serum immunoglobulin levels and impaired specific antibody responses. While immunoglobulin replacement therapy improves infection control, it has limited impact on phenotypic complications such as autoimmunity, polyclonal lymphoproliferation, enteropathy, and cytopenias, which may substantially affect patients’ quality of life (QoL). This study aimed to evaluate the relationship between distinct clinical phenotypes of CVID and QoL using the disease-specific CVID-QoL questionnaire. Materials and methods: This cross-sectional study included 30 adult CVID patients followed at the Immunology Clinic of Erciyes University Faculty of Medicine, diagnosed according to European Society for Immunodeficiencies criteria, and receiving regular intravenous immunoglobulin therapy. Demographic and clinical data were obtained retrospectively from medical records. Patients were classified into clinical phenotypes—uncomplicated, cytopenia, polyclonal lymphocytic inflammation (PLI), and enteropathy—based on dominant presentation at diagnosis. QoL was assessed using the CVID-QoL, which evaluates emotional functioning (EF), relational functioning (RF), and gastrointestinal/skin symptoms (GSS). Statistical analyses compared QoL scores across phenotypes. Results: The cohort comprised 16 females (53.3%) and 14 males (46.7%), with a mean age of 36.1 ± 11.2 years and a mean diagnostic delay of 11.7 ± 9.7 years. The most common phenotype was PLI (46.6%), followed by uncomplicated (36.6%), cytopenia (23.3%), and enteropathy (16.6%). Seven patients (23.3%) had 2 phenotypes simultaneously. Enteropathy phenotype was associated with significantly higher GSS scores ( P = 0.020). Patients with 2 phenotypes had significantly worse total CVID-QoL, EF, and GSS scores ( P = 0.006, 0.003, and 0.002, respectively), while RF scores were unaffected. Conclusion: Clinical phenotypes in CVID influence QoL to varying extents, with enteropathy and multiple concurrent phenotypes showing the greatest negative impact. These findings highlight the need for phenotype-based monitoring and targeted interventions to address both infection control and broader QoL determinants in CVID management.

This study aimed to determine the frequency of neutropenia in patients with common variable immunodeficiency (CVID) and investigate its relationship with disease prognosis. Data from 84 patients diagnosed with CVID and followed between 2019 and 2024 at the Department of Adult Clinical Immunology and Allergy, Necmettin Erbakan University, were retrospectively reviewed. Patients were divided into two groups based on the presence or absence of neutropenia. Demographic data, clinical findings, laboratory parameters, and survival rates were compared. Statistical analyses included the Mann-Whitney U test, the Chi-square test, and the Kaplan-Meier survival analysis. A total of 84 patients diagnosed with CVID were included in the study, with a median age of 38 years (range, 20-79 years). Of the participants, 48.8% were females (n = 41). Neutropenia was observed in 28.5% of patients (n = 24). The most common presenting complaints included autoimmune cytopenias, such as anemia and thrombocytopenia. Compared to non-neutropenic patients (n = 60), those with neutropenic CVID had a significantly higher mortality rate (33.3% vs 6.7%, P = 0.004). According to Kaplan-Meier survival analysis, the 8-year survival rates were 57.5 and 92.5% for neutropenic and for non-neutropenic CVID patients (p < 0.001), respectively. This study suggests that neutropenia in CVID patients may be more than just a hematological issue; it could also serve as an important clinical marker associated with increased mortality. Recognizing and closely monitoring neutropenia is essential for effective CVID management.

Common variable immunodeficiency (CVID) is one of the primary immunodeficiency disorders. The phenotype of peripheral blood memory B cells is a useful tool in the classification of patients into clinically and functionally relevant groups. This study aimed to assess the level of naïve and switched memory B cells level and their correlation with the clinical phenotypes and complications in patients with CVID. This case control study included 30 adult patients with CVID and 30 normal controls, matched for age and sex. Complete blood count, cluster of differentiation 3 (CD3)+, CD4+, CD8+ T cells and CD19+27-IgD+ for naïve B cells and CD19+27+IgD- switched memory B cells levels were assessed. The mean age of the onset of symptoms was 16.9±15.1 years, the mean age of diagnosis was 27.30±14.39 years, with a diagnostic delay of 10.43±10.29 years, and the body mass index was significantly lower in CVID group. Infections including (upper respiratory tract infection, chronic diarrhea, pneumonia and bronchiectasis) were the most frequent phenotypes. CD4+, CD4+/CD8+ T cells, CD19+ and CD19+27+IgD- switch memory B cell, IgG, IgA, and IgM were significantly lower in CVID group than in the control group (p < 0.001 and p < 0.015, respectively). CD8+ T cells and CD19+27-IgD+ naïve B cells were significantly higher in the CVID group (p < 0.001). CD19+27-IgD+ naïve B cells level was significantly lower in cases with bronchiectasis with low baseline serum IgG in lymphadenopathy group (p=0.049), and higher level of CD3+ T cells in cases with splenomegaly. There was no significant difference in laboratory results in CVID patients presented with autoimmune diseases, Granulomas nor enteropathy. In conclusion, high level of CD19+27-IgD+ naïve and low level of CD19+27+IgD- switch memory B cells are characteristic features of CVID. Moreover, the reduced CD19+27-IgD+ naïve B cells level can be a predictor of the development of bronchiectasis in CVID patients.

Introduction Common variable immunodeficiency (CVID) is a primary immunodeficiency characterized by low antibody levels. Immunophenotyping is crucial for classifying CVID patients and predicting severe complications by analyzing lymphocyte subsets. Methods Retrospective cohort of patients who fulfilled the 2019 European Society for Immunodeficiencies criteria for CVID and had performed a flow cytometry immunophenotype treated at a referral center in Buenos Aires. Results We analyzed 19 patients, of whom 10 were male and 9 female with a mean age of 51 years (20-66 years). The median follow-up was 12 years (6-35 years). Key findings included profoundly low CD19+ B cells (84.2%), decreased natural killer cells (68.4%), and inverted CD4/CD8 ratio (73.7%). T cell subpopulations showed a decrease in naive CD4+ T cells in 15 patients (78.9%); T helper (Th) profiles demonstrated skewing toward a Th1 profile in 12/13 patients (92.3%), accompanied by a decrease in Th2 and Th17 populations. Naive CD8+ T lymphocytes were decreased in 15/18 patients (83.3%) and increased in 3/18 (16.7%); effector memory cells were decreased in 2 (11.1%) and increased in 3 (16.7%). Terminal effector cells were decreased in 9 patients (50%) and increased in 9 patients (50%). Immune dysregulation (autoimmune cytopenias, granulomatous-lymphocytic interstitial lung disease, enteropathy) affected 52.6% of patients, 9/10 showed increased transitional B cells, 8/10 increased CD21low B cells, 8/10 a skewing to a Th1 profile, and 7/10 had an inverted CD4/CD8 ratio. 6/10 had decreased regulatory T cells (Tregs). Lymphoproliferation was present in 57.9%. Notably, 15.8% of the total cohort developed non-Hodgkin's lymphoma. 10/10 showed increased transitional B cells, 8/10 increased CD21low B cells, 9/9 presented a skewing to a Th1 profile, and 9/10 had an inverted CD4/CD8 ratio. Conclusion Immunophenotyping including T cell subsets may be useful to characterize CVID patients at risk of complex noninfectious complications.

Introduction IRF2BP2 was originally identified as a co-repressor of IRF2 in the JAK–STAT signaling pathway. Upon stimulation with type I or type II interferons (IFNs), STAT1 levels increase. STAT1 then forms either the ISGF3 complex (STAT1/STAT2/IRF9) or GAF (STAT1 homodimers), which translocate to the nucleus and bind ISRE or GAS sequences, respectively, to induce transcription of interferon-stimulated genes (ISGs). STAT1 also regulates IRF1 expression. IRF1 and IRF2 compete for the same ISRE regulatory elements but have opposing effects: IRF1 activates ISGs, while IRF2 represses them. Germline variants in IRF2BP2 have been linked to common variable immunodeficiency (CVID) and immune dysregulation. Results We functionally analyzed four novel heterozygous IRF2BP2 variants of uncertain significance, identified by whole exome sequencing in five patients presenting with isolated immune dysregulation, and one CVID patient with autoimmunity (P6, p.Glu253fs). P1 (p.Val7_Aladup) and P2 (p.Met192Ile) developed hemophagocytic lymphohistiocytosis. Inflammatory symptoms included skin and gastrointestinal involvement. P3, P4, and P5 (p.Ser501Ile) belong to the same family, all with arthritis and lymphoproliferation. To assess the functional impact of these variants, we examined IFN–JAK–STAT pathway activation in patient samples using droplet digital PCR. Our results revealed upregulation of STAT1 mRNA in all patients except P6. IRF1, a GAS-responsive ISG mainly induced by IFN-γ, was also elevated in most cases. Given IRF1’s role in amplifying ISG expression via ISRE binding, we measured expression of ISGs linked to type I (MX1, ISG15, IFIT1, RSAD2) and type II IFN signatures (IRF1, IRF8, GBP1, ICAM1). P6, the only patient without inflammation, showed normal signatures. In contrast, 4/5 patients with inflammatory symptoms had elevated IFN-α signatures, and all patients had increased IFN-γ signatures. Conclusion Our data reveal consistent hyperactivation of the IFN–JAK–STAT1 axis in IRF2BP2-deficient patients associated with inflammation. This aligns with IRF2BP2 loss-of-function variants lacking suppression of STAT1–IRF1 activity, suggesting dysregulated type I/II IFN signaling. JAK inhibitors may offer an effective therapeutic strategy.

Introduction Common variable immunodeficiency (CVID) is a highly heterogeneous immunodeficiency affecting individuals of all ages. We aim to characterize its clinical and immunological features throughout all stages of life. Methods We retrospectively reviewed patients with hypogammaglobulinemia evaluated at Hospital Italiano de Buenos Aires (2000–2025). After excluding secondary causes, only those fulfilling the 2019 European Society for Immunodeficiencies criteria for CVID were included and classified into three age-at-diagnosis groups: Group 1 (4–18 years), Group 2 (19–50 years), and Group 3 (51–80 years). Results Among 138 patients with hypogammaglobulinemia, 31 CVID patients from 30 families were included: 13 in Group 1, 11 in Group 2, and 7 in Group 3. The median follow-up was 8 years (interquartile range [IQR] 5–12). Group 2 had the longest diagnostic delay (median 6 years, IQR 4.5–19). Group 1 presented predominantly with infections and maintained this phenotype over a median of 14 years (IQR 4–22), except two patients with NFkB1 variants. Group 2 commonly exhibited combined infections and dysregulation, while Group 3 showed heterogeneous presentations. Bronchiectasis was diagnosed in three patients per group. Two patients developed lymphoma after age 40, and three in Group 3 developed solid tumors, all in remission. Notably, six patients in groups 2 and 3 had agammaglobulinemia with normal total B cells, of which two women (67 and 71 years) had no history of infections. Additionally, two female patients presented with hypogammaglobulinemia and absent B cells, with predominant multiorgan autoimmunity. No pediatric patients showed agammaglobulinemia at diagnosis. Genetic variants were identified in 3 of 10 tested patients: NFκB1 (two siblings), TRAF3, and a heterozygous variant of uncertain significance in DOCK8. No genetic studies were performed in Group 3. All patients are on immunoglobulin replacement therapy. One patient (aged 68) died from COVID-19. Conclusions Most childhood-onset CVID cases preserved their initial phenotype. In adults, unexplained agammaglobulinemia or absent B cells warrant genetic evaluation. In elderly patients, findings suggest late-onset rather than delayed diagnosis. Group 1 (4-18 years)Group 2 (19-50 years)Group 3 (51-80 years)n = 13n = 11n = 7Female sex*665Age at diagnosis13 (6-16)38 (33-40)60 (58-69)Current age27 (18-28)46 (39-49)71 (67-75)Follow-up14 (4-22)8 (5-10)5 (4.5-12.5)Diagnostic delay1 (0-4)6 (4.5-19)2 (0-4)Current phenotype*-Only infections812-Only dysregulation22-Both383-Asymptomatic2Phenotype progression*​​​-Only infections that adds dysregulation133-Dysregulation that adds infections11​Infections*1195-Sinusitis141-Otitis30​-Pneumonia964-Gastrointestinal1​Bronchiectasis*333Autoimmunity*385-Cytopenias223-IBD132-Hepatitis3-Alopecia areata11Lymphoproliferation292-Splenomegaly182-Granulomatous and lymphocytic interstitial lung disease2​Neoplasia*​-Lymphoma​11-Lung cancer​2-Prostate​1-Pre-neoplastic lesions (cervical or vulvar intraepithelial neoplasm)​2Median (interquartile range 25-75).*Absolute frequency.

Differences in immunoglobulin utilization when treating patients with primary immune disease in the United States

Splenomegaly represents a frequent non-infectious manifestation in Common Variable Immunodeficiency (CVID) and associates with specific clinical and immunophenotypic characteristics. To investigate the association between splenomegaly, infections, and immunophenotype in CVID patients. A cohort of 32 CVID patients (13 with splenomegaly) was enrolled. Infectious workup encompassed a detailed medical history and data derived from routine diagnostic assessments including specific virological analysis of blood and stool samples, and QuantiFERON assay for tuberculosis. Immunophenotype was assessed by multiparametric flow cytometry. Statistical analyses were performed using Prism and Jamovi software. CMV viraemia was detected in 40 % of splenomegalic CVID (sCVID) and was absent in non-sCVID patients. Of all infectious agents, CMV was the only one associated with splenomegaly (p = 0.009). The inclusion of CMV replication as a causative factor for splenomegaly in CVID is in line with the knowledge that splenomegaly is a hallmark of acute CMV infection and could help explain in the present CVID cohort 75 % of otherwise unexplained splenomegalies. Flow cytometric analysis in sCVID vs. non-sCVID confirmed decreases in NK cell numbers and activation, in circulating inflammatory precursors (Lin-CD16+), and increased T cell activation as defined by HLA-DR/CD69/CD38 expression. Splenomegaly in CVID patients may associate also with CMV replication. The combined identification in CMV+ sCVID of NK cell, inflammatory precursor and T cell imbalances suggests a possible combined cellular defect at precursor level in a subset of sCVID patients. When integrated into everyday clinical management, CMV viraemia could become a useful additional parameter for patient characterization and stratification.

Background. Common variable immunodeficiency (CVID) is the most frequent clinically symptomatic primary immunodeficiency; its clinical spectrum is highly variable, ranging from isolated recurrent infections to autoimmune (AID) and inflammatory rheumatic diseases (IRD), which may even be the unique manifestation at disease onset [1]. CVID is mainly a polygenic disease, even if recent studies employing whole-genome and exome sequencing analysis have highlighted that 15–30% may display a monogenic origin [2]. Aim of the study is to describe our CVID patients (pts) cohort, highlighting AID and IRD, and to describe genetic variants possibly linked to immunodeficiency and autoimmunity and therapeutic implications. Methods. This is a monocentric observational retrospective study considering CVID pts followed since 1985 to 2024. Diagnosis was made according to European Society for Immunodeficiency criteria [3]. A next generation sequencing (NGS) analysis of genes potentially linked to hypo-agammaglobulinemia and to antibody deficiency was executed when considered clinically appropriate. Results. Eighty-three pts with a CVID diagnosis were included. CVID total cohort description and comparisons between CVID pts with and without AID are reported in Table 1. Autoimmune cytopenia was the most common autoimmune manifestation occurring in 22.9% of the pts, with immune thrombocytopenia being the most prevalent. Immunosuppressive treatment was necessary in 89.5% of the pts affected by autoimmune cytopenia; in 5 cases, due to refractory cytopenia, rituximab was employed, achieving persistent remission in 4 pts. A diagnosis of IRD was made in 12 pts; 75.0% suffered from inflammatory arthritis. In one pt with Adenosine Deaminase 2 deficiency, genetic analysis aided in employing a target therapy leading remission of the IRD (Table 2). Genetic analysis for variants potentially leading to CVID had been performed in 37.3% of pts; analysis resulted positive in 41.9% of the tested. Genetic variants potentially linked to inborn errors of immunity (IEI) were found in more than half of pts with AID, much more frequently than in other CVID pts (56.5% vs 0.0%; p:0.010). The identified genetic variants are reported in Table 3. Conclusions CVID can be complicated by a wide spectrum of clinical pictures, including AID and IRD, being in our cohort inflammatory arthritis in most of the cases, categorized as a form of Spondyloarthritis in about two thirds. Notably, CVID pts affected by AID and IRD showed a higher frequency of genetic variants potentially leading to IEI; in one case genetic testing aided in orienting IS treatment, leading to remission of the IRD. Nowadays genetic analysis has still limited implications in influencing treatments in CVID, but in the future it might help in targeting precise mechanisms in patients with AID and IRD.

Introduction B cell subset enumeration by flow cytometric method has historically primarily existed to assist in the prognostic classification of common variable immunodeficiency (CVID) patients, and diagnostic reporting practices reflect this. Recently, there has been a noticeable increase in requests in the pediatric population for other indications that may require a different reporting strategy. Proposed indications include further immunophenotyping of inborn errors of immunity (IEIs), especially in humoral deficiencies or immune dysregulation disorders and/or monitoring for reconstitution following stem cell transplant (SCT) or immune-targeting therapies. Method A retrospective audit of paediatric patients (aged under 18 years) who had B cell subset enumeration performed at Immunopathology, Pathology Queensland Central Laboratory over a 12-month period between 1 January, 2024 and 31 December, 2024. We audited the demographics, ordering indication, ordering clinician specialty, concurrent immunoglobulin levels, B cell subsets, and whether the result contributed to diagnosis or management. Results There were 97 distinct B cell subset tests from 95 separate patients. 34 patients were excluded due to insufficient clinical information. Most requests were for assessment of humoral immunodeficiency, either immune phenotyping in a known diagnosis or screening in suspected cases. Conclusion This audit demonstrated that the majority of paediatric requests for B cell subset enumeration are not for CVID subclassification and are for broader indications. This highlighted the need to update B cell subset reporting strategies to greater reflect these indications and assist the clinical application.

Common Variable Immunodeficiency (CVID) is a group of heterogeneous disorders with common denominators of impaired antibody production and function, and recurrent infections. Currently, prognostic biomarkers for CVID are limited. CXCL13 is a critical regulator of germinal centre responses and antibody production, with T follicular helper (Tfh) cells as a major source, and acts as a potent B cell chemoattractant. Serum levels of CXCL13 are increased in chronic inflammatory conditions and malignancy. We aimed to explore whether serum CXCL13 levels are altered in CVID and whether they can categorise the patients based on their clinical and immune phenotype. We compared the serum levels of CXCL13 between CVID and healthy donors (HD) and associated them with the clinical and immune phenotype of the patients. The serum levels of CXCL13 were higher in CVID, especially in female patients, as compared to HD, and were positively correlated with the number of clinical complications in CVID and the total peripheral circulating Tfh cells (cTfh). CVID patients with higher levels of CXCL13 were more likely to have clinical complications and/or high frequency of CD21low B cells or low frequency of switched memory B cells. CXCL13 can categorise heterogeneous patients with CVID and be used as a biomarker of complex disease.

Abstract Description Common variable immunodeficiency (CVID) is a common inborn error of immunity, but a monogenic cause is rare. Biallelic loss-of-function pathogenic variants in the gene encoding BAFF-Receptor (TNFRSF13C) is one such cause. A common missense variant in BAFF-R, p.Pro21Arg, was proposed as contributing to the pathogenesis of non-monogenic CVID by Peiper et al. 2014 with an allelic frequency of 6.7% in controls versus 10.2% in CVID patients (OR 1.57, p = 0.0026) and Block et al. 2023 with an 11.36% allele frequency in CVID when compared to the Non-Finnish European population in the gnomAD database (OR = 1.316, p = 0.0145) and to an internal cohort of controls (OR = 1.316, p = 0.0458). Exact population composition matching is critical, as the frequency of this variant is highly variable even in Europe. We found the allelic frequency of BAFF-R p.Arg21Pro to be 10% from 90 non-familial CVID patients from the University of Utah Health Sciences Center, similar to Pieper et al. (10.2%) and Block et al. (11.36%), but comparing our Utah CVID patients to the 1000 Genomes project Utah Residents (CEU) with Northern and Western European Ancestry, which matches our CVID cohort (9.6% allelic frequency); we obtained an OR of 1.0468 (95% CI: 0.5309 to 2.0638; p = 0.8950). For further studies on BAFF-R p.Pro21Arg, we recommend closely matching the reference populations, and not using a broad European or other control populations. Topic Categories Translational and Interventional Immunology (TI)

Background: Common variable immunodeficiency (CVID), the most prevalent symptomatic inborn error of immunity, involves impaired B-cell differentiation and antibody production, causing recurrent infections and the need for life-long immunoglobulin replacement therapy. Methods: This study evaluated the in vitro differentiation of memory B-cells (MBCs) into antibody-secreting cells (ASCs) in CVID patients. Peripheral blood mononuclear cells from 13 CVID patients and 10 healthy controls were stimulated using two protocols: (I) Staphylococcus aureus Cowan Strain I, Pokeweed mitogen, and CpG, or (II) a T-cell-dependent approach using CD40 ligand, interleukin-21, and CpG. B-cell subpopulations were analyzed by flow cytometry, ASC differentiation using ELISpot, and antibody levels in supernatants by ELISA. Results: Despite severely restricted in vivo antibody production, MBCs from all 13 CVID patients differentiated into IgG and IgM ASCs under adequate in vitro stimulation. Protocol II, mimicking T-cell help, was more effective than protocol I. As expected, the patients exhibited reduced class-switched MBCs ex vivo, but the MBCs differentiated and proliferated to an extent similar to those in healthy controls. IgA secretion remained significantly impaired post-stimulation. Specific IgG antibodies against tetanus toxoid and Streptococcus pneumoniae were detected in the patient supernatants, while no double-stranded DNA autoantibodies emerged after in vitro stimulation. Conclusions: These findings indicate that the MBCs of most patients retain functional B-cell differentiation and antigen-specific IgG secretion under T-cell dependent stimulation, though IgA secretion remains impaired. Tailored stimulation protocols could deepen our understanding of how to restore MBC formation in CVID patients in vivo. This methodology provides a platform to investigate antigen-specific functional memory responses like post-vaccination.